Assumptions:
Battery is fully charged
(high current testing requires constant attention to charging)
(battery depletes fast with two 40A breakers cycling;
good 40A breakers open @ ~50A ea x 2 = 100A,
and open at lower currents as cycled more frequently)
BTW:
18AH SLA battery is discharged in 3 minutes at 54A to 8V !!!
see the mfr discharge curves to verify, docs: 18ahExide.pdf
so at 100A continuous expect only a couple minutes at full energy.....
DO measure the current where the breakers open, (on full batt charge)
last year we found many 40A rated opened at 30A (~26A rating)
How ??
Use a DVM, 200mV scale connected across the 120A main breaker.
when ckt bkr closed the current is ~1A for each mV on the DMM !!!
A 3 digit DMM will thus read +- 199.9A
(The open ckt bkr reads ~12.6v, which will not harm a DMM)
First impression from photo's:
with 12" wheels you are geared too high
(are other wheels unrestricted castors ?
if so it should do circles rather well,
but may be hard to drive straight line)
use smaller wheels 3" would move well
or Gear Down 3:1, 4:1
I know neither is attractive at this point, sorry....
[IMG]F:/Robotics/2004/MANUAL/18ahExideDischgCurves.jpg[/IMG]